Effective laser driven proton acceleration from near critical density hydrogen plasma

Abstract

Recent advances in the production of high repetition, high power, and short laser pulse have enabled the generation of highenergy proton beam, required for technology and other medical applications. Here we demonstrate the effective laser driven proton acceleration from near-critical density hydrogen plasma by employing the short and intense laser pulse through three-dimensional (3D) particle-in-cell (PIC) simulation. The generation of strong magnetic field is demonstrated by numerical results and scaled with the plasma density and the electric field of laser. 3D PIC simulation results show the ring shaped proton density distribution where the protons are accelerated along the laser axis with fairly low divergence accompanied by off-axis beam of ring-like shape.

High Energy electron and proton acceleration by circularly polarized laser pulse from near critical density hydrogen gas target

“…The spatio-temporal intensity profile of laser is considered as Gaussian distribution and can be written as , where r 0 is the transverse radius of laser beam and τ 0 is laser pulse duration. For optimum acceleration in case of MVA 23 , the laser spot size should match the size of the self-focusing channel in order to avoid filamentation. The laser beam radius in an underdense plasma can be written as where is the critical power and is the Rayleigh range.…”

“…The effectiveness of MVA mechanism requires the efficient transfer of laser energy to the fast electrons in the plasma, which are accelerated in the plasma channel along the laser propagation direction. The optimum plasma length 23 can be estimated from the assumption that all laser energy is transferred to the electrons in the plasma channel, where K is the geometry constant ( K is 0.1 in 2D case and 0.074 in 3D case), is the normalised electric field amplitude of laser, e & m e are fundamental charge and electron mass, E L is the laser electric field, ω 0 is the laser frequency and c is the speed of light in vacuum.…”

“…7 . In our previous research 23 , we demonstrated the proton acceleration via MVA mechanism with tightly focused LP laser pulse (2PW-20fs) interaction with near critical density plasma (~3.0 n c ). Simulation results in this regime shows comparatively lower laser-to-proton conversion efficiency ~1% (for protons with energy > 4 MeV) but higher peak proton energy ~GeV.…”

“…The highest proton beam quality has been observed when applying solid-density planar target geometries 30 ; so far the highest proton energies experimentally achieved with TNSA are 85 MeV 31 . In our previous research 23 , we demonstrated the proton acceleration via MVA mechanism with tightly focused LP laser pulse (2PW-20fs) interaction with NCD plasma (~3.0 n c ). Simulation results in this regime shows comparatively lower laser-to-proton conversion efficiency ~1% (for protons with energy >4 MeV) but higher peak proton energy.…”

High quality ion acceleration through the interaction of two matched counterpropagating transversely polarized Gaussian lasers with a flat foil target

“…Compared with the traditional particle accelerators, the laser plasma accelerator has some advantages in the ultrahigh accelerating gradient, smaller size, and relatively lower cost [4]. For now, some acceleration mechanisms have been proposed, for example, electrostatic shock acceleration (ESA) [5][6][7][8][9], target normal sheath acceleration [10][11][12][13], magnetic vortex acceleration [14][15][16][17][18], and radiation pressure acceleration (RPA) , etc. Among these mechanisms, the RPA is regarded as one of the most promising schemes because of its high energy conversion efficiency and the excellent quality of the accelerated ions [19,29,30].…”